Color imaging device and method

ABSTRACT

A color imaging method for adjusting color balance of an imaged picture of an object, which object is imaged by a camera head  3  for generating color imaging signals composed of plural color signals. Based on the relative relation between signal levels of the color signals, level balance control data are generated by an information processing device  5.  The level balance control data, generated by the information processing device  5,  is stored in LUTs  45 R,  45 G and  45 B, in association with the signal level of plural color signals in each of plural light exposure volumes adjusted by the light stop of an imaging lens  2  adapted for adjusting the light exposure volume of the camera head  3  or the signal charge accumulating time of a CCD image sensor  21.  Based on the signal levels of the color signals, the level balance control data associated with the color signals are read out from the LUTs  45 R,  45 G and  45 B for controlling the signal levels of the color signals. The color balance can be adjusted even in a grey area intermediate between the black and the white which has not been possible to achieve with the conventional white balance adjustment.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] This invention relates to a color imaging device and method foradjusting color balance of an imaged still picture.

[0003] 2. Description of the Related Art

[0004] In a camera device, pre-set color reproducibility is achieved byeffecting white balance adjustment and black balance adjustment, evenalthough the color temperature of an object differs from one lightsource to another.

[0005] In effecting white balance adjustment, a white object is imaged,and level adjustment is performed so that the signal levels of colorsignals in the white luminance point will be equal to one another. Ineffecting black balance adjustment, the black level of imaging signalsis sampled by once closing a lens shutter and adjusting the signal levelso that the black levels of the respective color signals will be equalto one another.

SUMMARY OF THE INVENTION

[0006] It is therefore an object of the present invention to provide acolor imaging device and a color imaging method whereby it is possibleto effect color balance in a grey area intermediate between the blackand white which has not been possible with conventional white balanceadjustment.

[0007] It is another object of the present invention to provide a colorimaging device and a color imaging method whereby it is possible toperform color balance adjustment in all grey areas including the blackand white.

[0008] In one aspect, the present invention provides a color imagingapparatus including imaging means for imaging an object for generating acolor imaging signal made up of a plurality of color signals, levelbalance control data generating means for generating level balancecontrol data based on the relative relation between signal levels of thecolor signals, light exposure volume adjustment means for adjusting thelight exposure volume of the imaging means, memory means for storing, ineach light exposure volume adjusted by the light exposure adjustmentmeans, the level balance control data generated by the level balancecontrol data generating means, in association with signal levels of thecolor signals in each light exposure volume, and level balance controlmeans for reading out the level balance control data associated with thecolor signals from the storage means, based on the signal level of eachof the color signals, for controlling the signal level of each colorsignal. This enables color balance adjustment in a entire grey areabetween black and white which has not been possible to perform inconventional white balance adjustment.

[0009] In another aspect, the present invention provides a color imagingapparatus including imaging means for imaging an object for generating acolor imaging signal made up of a plurality of color signals, pre-setarea extraction means for sequentially extracting color imaging signalsof portions representing images in a plurality of pre-set areas in apicture represented by the color imaging signals, level balance controldata generating means for generating level balance control data based onthe relative relation between signal levels of the color signalscontained in the pre-set areas, storage means for storing the levelbalance control data in association with the relative relation of thesignal levels of the color signals contained in the preset areas, andlevel balance control means for reading out the level balance controldata from the storage means in association with the color signals basedon the signal levels of the color signals for controlling the signallevels of the color signals. This enables automatic color balanceadjustment in a entire grey area between black and white.

[0010] In still another aspect, the present invention provides a colorimaging apparatus including imaging means for imaging an object forgenerating color imaging signals made up of a plurality of colorsignals, display means for displaying an image based on the colorimaging signals, area designation means for designating a desired areain the image displayed by the display means, level balance control datagenerating means for generating level balance control data based on therelative relation between signal levels of the color signalsconstituting the color imaging signals corresponding to the areadesignated by the area designating means, storage means for storing thelevel balance control data in association with the signal levels of thecolor signals in the area designated by the area designating means, andlevel balance control means for reading out the level balance controldata associated with respective color signals from the storage meansbased on the signal levels of the color signals for controlling thesignal levels of the color signals. This enables color balanceadjustment in a entire grey area between black and white by a simplifiedoperation.

BRIEF DESCRIPTION OF THE DRAWINGS

[0011]FIG. 1 is a schematic block diagram showing the configuration ofan imaging system embodying the present invention.

[0012]FIG. 2 is a block diagram showing an illustrative structure of acolor imaging device in the imaging system of FIG. 1.

[0013]FIG. 3 is a schematic block diagram showing an illustrativeconfiguration of a digital processor of the color imaging device shownin FIG. 2.

[0014]FIG. 4 is a block diagram showing the configuration of a LUTprovided in the digital processor of FIG. 3.

[0015]FIG. 5 is a flowchart showing the method for adjusting the colorbalance in the imaging system of FIG. 2.

[0016]FIG. 6 illustrates the display contents of a display of aninformation processing apparatus in the imaging system of FIG. 2.

[0017]FIG. 7 illustrates the display contents of a display of theinformation processing apparatus shown in FIG. 6.

[0018]FIG. 8 is a flowchart showing the sequence of automatic adjustmentof color balance in the imaging system of FIG. 2.

[0019]FIG. 9 is a flowchart showing the sequence of automatic adjustmentof color balance in the imaging system of FIG. 2.

[0020]FIG. 10 illustrates the display contents of the display of theinformation processing apparatus shown in FIG. 6.

[0021]FIG. 11 similarly illustrates the display contents of the displayof the information processing apparatus shown in FIG. 6.

[0022]FIG. 12 is a graph showing characteristics of the usual LUT in theimaging system of FIG. 2.

[0023]FIG. 13 is a graph showing characteristics of the LUT withnegative-positive inversion in the imaging system of FIG. 2.

[0024]FIG. 14 is a flowchart showing another method for adjustment ofthe color balance in the imaging system of FIG. 2.

[0025]FIG. 15 is a flowchart for illustrating the sequence offormulating color balance correction data.

[0026]FIG. 16 is a flowchart for illustrating the sequence of whiteluminance level setting.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0027] Referring to the drawings, preferred embodiments of the presentinvention will be explained in detail. The present imaging system hasthe function of performing fine adjustment in white balance adjustment(grey balance adjustment) at the time of fine gamma adjustment for colorimaging signals of red (R), green (G) and blue (B) obtained on imagingan object by a color imaging device 1 for effecting level balanceadjustment for color signals for all intermediate colors from white toblack.

[0028] The color imaging device 1 of the present imaging system includesa camera head 3 for imaging an object via an imaging lens 2 foroutputting imaging signals, and a digital processor 4 for converting thecolor imaging signals from the camera head 3, storing the convertedimaging data, supplying the stored picture data to an informationprocessing device 5 and for effecting color signal level balanceadjustment for the stored imaging data.

[0029] The imaging system also includes an information processing device5 for controlling data processing by the digital processor 4, a printer6 for outputting an image of the object based on the imaging datatransmitted from the color imaging device 1. The imaging system furtherincludes a personal computer 7 for performing a control similar to thatperformed by the information processing device 5 and a monitoring device8 for displaying an image of the object imaged by the camera head 3.

[0030] The imaging system also includes a remote controller 9 forperforming flash synchronized imaging, and a liquid crystal display(LCD) view finder 10 for displaying the image of the object imaged bythe camera head 3. The imaging system also includes a strobo generator11 and a strobo light emitting device 12 which emits flash light if, incase of necessity, a release button 9A of the remote controller 9 ispressed.

[0031] Specifically, the camera head 3 includes a charge coupled device(CCD) image sensor 21, a correlated double sampling (CDS) circuit 22, apre-amplifier 23, a gain control circuit 24, a white balance circuit 25,a pre-knee circuit 26, a gamma correction circuit 27 and an outputdriver 28, as shown for example in FIG. 2.

[0032] The CCD image sensor 21 is of a progressive scan type three CCDplate system designed for reading out color imaging signals of red (R),green (G) and blue (B) responsive to three prime color componentsseparated by a color separation prism 37 from the imaging light incidentthereon from the imaging lens 2 via an optical low-pass filter 36.

[0033] The CDS circuit 22 performs correlated double sampling on thecolor imaging signals R, G and B read out from the CCD image sensor 21to send color imaging signals R, G and B, reduced in random noise, tothe pre-amplifier circuit 23.

[0034] The color imaging signals of R, G and B, amplified by thepre-amplifier circuit 23, has its gain controlled by the gain controlcircuit 24 controlled by the CPU 30. The gain-controlled color imagingsignals are routed to the white balance circuit 25.

[0035] The white balance circuit 25 performs white clip on the colorimaging signals, if need be, and routes the processed color imagingsignals R, G and B to the pre-knee circuit 26.

[0036] The pre-knee circuit 26 compresses the signal level of the colorimaging signals R, G and B higher than a pre-set knee level and routesthe compressed signals to the gamma correction circuit 27. This gammacorrection circuit 27 performs signal level conversion based on, forexample, a 0.45 γ non-linear curve in order to route the color imagingsignals R, G and B via output driver 28 and terminals 29A, 29G and 29Bto the digital processor 4.

[0037] The camera head 3 includes a micro-computer (CPU) 30 forcontrolling the gain control circuit 24, white balance circuit 25,pre-knee circuit 26 and the gamma correction circuit 27, an electricallyerasable programmable ROM (EEPROM) 31 for holding on memory a controlprogram for the CPU 30, and a sync generator 33 for generatingsynchronization signals. The camera head 3 also includes a timinggenerator 34 for generating CCD readout pulses based on thesynchronization signals from the sync generator 33 and a CCD driver 35for amplifying CCD readout pulses from the timing generator 34.

[0038] The CPU 30 controls gamma correction, generation ofsynchronization signals by the sync generator 33 or the diaphragm of theimaging lens 2 based on the control signals supplied from the digitalprocessor 4 via terminal 32 and the control program stored in the EEPROM31.

[0039] The sync generator 33 generates vertical and horizontalsynchronization signals and routes these synchronization signals to thetiming generator 34. The timing generator 28 generates CCD readoutpulses, vertical transfer pulses and horizontal transfer pulses based onthese synchronization signals. The CCD driver 29 drives the CCD imagesensor 21 by these CCD readout pulses. Th CCD image sensor 21 thusoutputs color imaging signals R, G and B at a rate of 24 frames persecond.

[0040] Referring to FIG. 3, the digital processor 4 includes amplifiers42R, 42G and 42B for amplifying the color imaging signals R, G and Bsupplied form the camera head 3 and cable compensators 43R, 43G and 43Bfor compensating the cable length for the color imaging signals from theamplifiers 42R, 42G and 42B. The digital processor 4 also includesanalog/digital (A/D) converters 44R, 44G and 44B for converting thecolor imaging signals R, G and B from the cable compensators 43R, 43Gand 43B and lookup tables (LUTs) 45R, 45G and 45B for converting thegradation of the color imaging data from the A/D converters 44R, 44G and44B.

[0041] The cable compensators 42R, 42G and 42B are fed with colorimaging signals R, G and B from the camera head 3 via terminals 41R, 41Gand 41B and amplify these color imaging signals R, G and B to supply theamplified signals to the cable compensators 43R, 43G and 43B.

[0042] The cable compensators 43R, 43G and 43B compensate fordeterioration in frequency characteristics responsive to the cablelength for the amplified color imaging signals and route the respectiveproduced color imaging signals to the A/D converters 44R, 44G and 44B.

[0043] The A/D converters 44R, 44G and 44B convert the color imagingsignals into color imaging data composed of 10-bit samples, usingsampling clocks, not shown, based on the synchronization signals fromthe camera head 3, and route the color imaging data to the LUTs 45R, 45Gand 45B.

[0044] The LUTs 45R, 45G and 45B store level conversion data as tabledata in order to perform grey balance correction of color imaging datagamma-corrected by the gamma correction circuit 27. The LUTs 45R, 45Gand 45B are made up of level detectors 451R, 451G and 451B fed with10-bit color imaging data from the A/D converters 44R, 44G and 44B andtable memories 452R, 452G and 452B, from which table data are read,using the detection outputs by the level detectors 451R, 451G and 451Bas readout addresses, as shown in FIG. 4. As the table memories 452R,452G and 452B, a 512K 8 bit static random access memory (SRAM) is usedfor each of the table memories 452R, 452G and 452B. In this SRAM isstored, as table data, 8-bit level conversion data supplied from arandom access memory (RAM) 67 via a buffer memory 65.

[0045] The LUTs 45R, 45G and 45B convert the 10-bit color imaging datasupplied from the A/D converters 44R, 44G and 44B into 8-bit colorimaging data which are supplied to a write control circuit 46 and adynamic random access memory (DRAM) controller 55.

[0046] The digital processor 4 includes a write control circuit 46 forcontrolling the writing of the color imaging data R, G and B from theLUTs 45R, 45G and 45B and a video random access memory (RAM) 47 forstoring the color imaging data under control by the write controlcircuit 46. The digital processor 4 also includes a readout controlcircuit 48 for controlling readout of the color imaging data read outfrom the VRAM 47 and LUTs 49R, 49G and 49B for converting the gradationof the color imaging data read out from the readout control circuit 48.The digital processor 4 further includes converters 51R, 51G and 51B forconverting the color imaging data R, G and B from the LUTs 49R, 49G and49B into color imaging signals 51R, 51G and 51B, low-pass filters (LPFs)52R, 52G and 52B for allowing passage only of color imaging signals of aspecified band, and a matrix encoder 53.

[0047] The write control circuit 46 transmits readout clocks of 30 MHZto the VRAM 47, while reading out color imaging data R, G and B at arate of 30 frames per second in synchronism with the readout clocks forsupplying the color imaging data to the LUTs 49R, 49G and 49B. Thereadout control circuit 48 routes the 30 MHZ write clocks to the VRAM47, while reading out the color imaging data from the VRAM 47 at a rateof 30 frames per second in synchronism with the readout clocks forsupplying the color imaging data R, G and B to the LUTs 49R, 49G and49B.

[0048] The LUTs 49R, 49G and 49B are each made up of a 512K 8 bit SRAMfor storing LUT data supplied from the RAM 67 via buffer memory 66.Specifically, the LUTs 49R, 49G and 49B hold on memory as table datasuch characteristic data in which color regeneration of the monitoringdevice 8 and gradation regeneration (picture quality) will be equal tothe picture quality displayed on a CRT of a display of the informationprocessing device 5 or with the picture quality of the picture printedout by the printer 6, and perform level correction of color imaging databy these characteristic data. The LUTs 49R, 49G and 49B convert thegradation of the color imaging data R, G and B independently of oneanother in order to route the resulting color imaging data to the D/Aconverters 51R, 51G and 51B, respectively.

[0049] The D/A converters 51R, 51G and 51B convert the color imagingdata, made up of 8-bit samples, into color imaging signals R, G and Bwhich are then supplied to the LPFs 52R, 52G and 52B, respectively. Inthe upstream stage of the D/A converters 51R, 51G and 51B are providedadders 50R, 50G and 50B supplied with menu data read out from the ROM 68in which is pre-stored a program designed to control the overall system.

[0050] The LPFs 52R, 52G and 52B allow for passage only of a pre-setband of the color imaging signals R, G and B to eliminate unneeded bandcomponents and routes the resulting color imaging signals to the matrixencoder 53.

[0051] The matrix encoder 53 converts the color imaging signals R, G andB into, for example, luminance signals Y and chroma signals C andprocesses these signals Y and C into composite color video signals of,for example, the NTSC system, in order to supply the color signals viaterminal 54 to the monitor device 8. The matrix encoder 53 can alsooutput the color imaging signals R, G and B directly. This enables animage corresponding to the signals from the color imaging device to bedisplayed on the monitor device 8.

[0052] The digital processor 4 includes a frame memory 56, a framememory 57, as a spare for this frame memory, and a DRAM controller 55for writing color imaging data on the frame memories 56, 57 for readingout color imaging data from the frame memories 56, 57.

[0053] The frame memory 56 includes a DRAM 56R for holding the colorimaging data R on memory, a DRAM 56G for holding the color imaging dataG on memory and a DRAM 56B for holding the color imaging data B onmemory. Each of the DRAMs 56R, 56G and 56B can hold on memory colorimaging data of, for example, 1280 960 pixels. The color imaging data R,G and B from the DRAMs 56R, 56G and 56B are read out from or written inthe frame memory 56 under control by the DRAM controller 55.

[0054] The DRAM controller 55 is configured for writing the colorimaging data R, G and B from the LUTs 45R, 45G and 45B in the framememory 56, or for reading put color imaging data from the frame memory56. The DRAM controller 55 is configured for decimating the colorimaging data stored in the frame memory 56 for reading out 640 480pixels of color imaging data.

[0055] The frame memory 57 is configured similarly to the frame memory56 and is provided as a spare for the frame memory 56.

[0056] The digital processor 4 includes an averaging circuit 58 forremoving redundant high frequency range of the color imaging data fromthe DRAM controller 55, and an interpolation circuit 59 forinterpolating the color imaging data from the DRAM controller 55 foroutputting luminance data Y. The digital processor 4 also includes apicture quality adjustment and contrast adjustment circuit 60 forincreasing the acuteness of picture quality of the luminance data Y fromthe interpolation circuit 59 and for adjusting the contrast, and amatrix circuit 61. The digital processor 4 further includes a maskingcircuit 62 for broadening the frequency width of respective colorimaging data from the matrix circuit 61 and a SCSI (small computersystem interface) protocol controller (SPC) 63 operating as an interfacefor signal transmission/reception over an SCSI bus.

[0057] The averaging circuit 58 removes unneeded high frequency bandcomponents of the color imaging data R, G and B, for preventing aliasingof the high frequency band signal components to the signal components ofthe low frequency band and routes the color imaging data R, G and B tothe matrix circuit 61.

[0058] The interpolation circuit 59 interpolates the color imaging datafor improving resolution and converts the interpolated color imagingdata R, G and B into image data Y, U and V. The interpolation circuit 59also transmits the luminance data Y to the picture quality adjustmentand contrast adjustment circuit 60, while routing the chroma data U andV to the matrix circuit 61.

[0059] The picture quality adjustment and contrast adjustment circuit 60acquires contour signals by a high-pass filter from, for example,luminance data Y, and removes the noise contained in the contour signalsby a core ring. After amplitude adjustment, the circuit 60 sums theresulting signal to the main signal for adjusting the picture quality.The picture quality adjustment and contrast adjustment circuit 60 variesthe gain of the luminance data Y and moderately varies the amplitude forcontrast adjustment. The contrast-adjusted luminance data Y is fed tothe matrix circuit 61.

[0060] The matrix circuit 61 can output one of the supplied colorimaging data R, G and B and picture data Y, U and V. For example, thematrix circuit 61 outputs the color imaging data R, G and B to themasking circuit 62.

[0061] The masking circuit 62 widens the band of the supplied colorimaging data R, G and B for increasing the saturation for enhancingflashiness of the colors. In addition, the masking circuit 62 transmitsthe resulting color imaging data R, G and B via SPC 63 to, for example,the information processing device 5.

[0062] The digital processor 4 includes a buffer memory 65 for writinglevel conversion data in the LUTs 45R, 45G and 45B and a buffer memory66 for writing level conversion data in the LUTs 49R, 49G and 49B. Thedigital processor 4 also includes a RAM 67 for holding on memory thedata of the LUTs 45 and 49, a ROM 68 in which a program for controllingthe overall system is stored, and a CPU 69 for executing the programwritten in the ROM 68.

[0063] With the above-described imaging system, a picture correspondingto the object is displayed on the monitor device 8. If the user pressesa release button 9A as he or she views the monitor device 8, the colorimaging data is stored in the frame memory 56. The color imaging datastored in the frame memory 56 is transferred over an SCSI bus to theinformation processing device 5 which can perform color balanceadjustment thereon. The printer 6 is adapted for printing out a stillpicture based on the color imaging data.

[0064] Specifically, with the present imaging system, the user preparesthe object at step S1 and adjusts the focusing or the angle of field ashe or she views a moving picture displayed on the viewfinder 10 or onthe monitor device 8, while checking the light stop value. On the otherhand, menu data is read out from the ROM 68 in which the program forcontrolling the overall system is read out and sent to the adders 50R,50G and 50B, so that the user can actuate a button of the remotecontroller 9 for setting the imaging conditions as he or she views themenu representation, not shown, of the camera sensitivity or the lightexposure system.

[0065] With the present imaging system, the user presses at step S2 therelease button 9A of the remote controller 9A for supplying a releasesignal to the CPU 30 of the camera head 3 for imaging an object. Theimaging signals produced by the camera head 3 are fed to the digitalprocessor 4 which then writes the color imaging signal converted by thedigital processor 4 into digital signals via DRAM controller 55 in theframe memory 56.

[0066] Are the next step S3, the color imaging data written in the framememory 56 are read out and imaging signals are supplied to the monitordevice 8 from the matrix encoder 53 via terminal 54. The user views animage displayed on the monitor device 8 and transfers the image to theinformation processing device 5.

[0067] At the next step 4, the user clicks a ‘transfer’ button 9C on theremote controller 9 or a ‘transfer’ button 75 on a display screen of theinformation processing device 5. This routes the transfer command signalto the CPU 30 of the camera head 3. The transfer command signal is sentvia terminal 32 to the CPU 69 of the digital processor 4. Under controlby the CPU 69, the DRAM controller 55 decimates and reads out colorimaging data stored in the frame memory 56. For example, 1280 960 pixelcolor imaging data have been written in the DRAMs 56R, 56G and 56B ofthe frame memory 56. These color imaging data R, G and B are decimatedby the DRAM controller 555 reading out 640 960 pixel color imaging data.The read-out color imaging data R, G and B are directly outputted by thematrix circuit 61 so as to be transferred via making circuit 62 and SPC63 to the information processing device 5.

[0068] When the color imaging data R, G and B have been transferred fromthe digital processor 4 to the information processing device 5, thedevice 5 is in a stand-by state in readiness for auto/manual selectionsetting, with the picture derived from these color imaging data R, G andB being displayed on the display 5A.

[0069] That is, the present imaging system is configured for adjustingcolor balance of the color imaging data R, G and B based on the colorbalance adjustment control from the information processing device 5.

[0070] The color balance adjustment by the information processing device5 is classified into standard object correction of doing color balanceadjustment at an optional intermediate level from black to white, andgeneral object correction of doing color balance adjustment at anoptional point of an image being formed.

[0071] In the case of the standard object correction, a grey scale isimaged by the camera head 3. At this time, there are displayed, on thedisplay 5A of the information processing device 5, a display portion 71displaying the grey scale consisting of 11 areas gradually changed fromblack to white, an iris registration portion 72, having registeredtherein pre-set values of iris of the imaging lens 2, an iris adjustmentportion 73, an iris setting portion 74, an adjustment data transferportion 75 for transferring adjustment data to the color imaging device1 after color balance adjustment, a release portion 76, a level/memoryselection portion 77 for switching between a level image and a storedimage, a coordinate display portion 78 for displaying the coordinate ofa side of the display portion 71 pointed by a mouse 5C, a level displayportion 79 for displaying level values of the color signals R, G and B,and an auto-manual selection portion 80 for selecting whether colorbalance adjustment is to be performed automatically or manually, asshown for example in FIG. 6.

[0072] In the case of general object correction, a decimated objectimage is displayed on the display portion 71, as shown for example inFIG. 7. Switching between the standard object correction and the generalobject collection may be achieved using, for example, the remotecontroller 9.

[0073] The user can designate a point of a picture displayed on thedisplay portion 71 of the display 5A using, for example, the mouse 5C,as shown for example in FIG. 6.

[0074] In the standard object correction, if the user clicks an optionalpoint of the display portion 71 to designate the grey level for greybalance adjustment, the information processing device 5 can displayrespective signal levels of the color imaging signals R, G and B at thedesignated positions on the level display portion in terms of valuesfrom 0h to FFh.

[0075] Similarly, in the general object correction, if the user clicksan optional point of the display portion 71 to designate the grey levelfor grey balance adjustment, the information processing device 5 candisplay respective signal levels of the color imaging signals R, G and Bat the designated positions on the level display portion in terms ofvalues from 0h to FFh.

[0076] If the user clicks a mark in the iris registration portion 72, apreviously registered iris value is displayed. If the user re-clicks adesired one of the registered iris values, the information processingdevice 5 transmits data of the clicked iris values to the CPU 30 of thecamera head 3 for adjusting the iris of the imaging lens 2. The user maysimilarly drag a short crossbar of the iris adjustment portion 73towards left or right for doing iris adjustment.

[0077] Referring to the flowchart of FIG. 8, if, in the above-mentionedstand-by state, the user clicks the auto/manual selection portion 80 atstep S11, the information processing device 5 proceeds to step S12 inorder to judge whether or not auto has been selected.

[0078] If auto is selected, the information processing device 5transfers to step S13 for doing automatic grey balance adjustment.Conversely, if manual is selected, the information processing device 5transfers to step S14 to await designation of the correction point.

[0079] The processing for automatic grey balance adjustment at step S13takes place in case of imaging a standard object which gives the greyscale comprised of 11 areas exhibiting gradual transition from black towhite, as displayed on the display portion 71 shown in FIG. 6.Specifically, the processing occurs in accordance with the flowchartshown in FIG. 9.

[0080] The black area and the white area in the grey scale are demotedby area numbers A=1 and A=11, with the intermediate grey areas beingdenoted as A=2 to 10.

[0081] At the first step S21, an area number is initialized (A=1) and,at the second step S22, G-R and G-B are calculated, based on the colorimaging data R, G and B of an area denoted by area number A. At the nextstep S23, correction data is found, based on the results of thecalculations. The correction data is stored n association with the areanumber A. Such association with the area number A is equivalent toassociation with the signal level values of the color imaging signals R,G and B.

[0082] At the next step S24, it is judged whether or not the area numberis equal to ‘11’. If A≠11, the information processing device 5 transfersto step S25 to increment the area number A (A=A+1). The informationprocessing device 5 then reverts to step S22 to process the next area.The correction data is sequentially found for each of areas of the greyscale. If it is found at step S24 that A=11, the information processingdevice 5 reverts to step S26 to generate LUT table data. The informationprocessing device 5 then transfers to step S16 in the flowchart of FIG.8.

[0083] At step S16, the information processing device 5 sends a commandof re-writing the LUT table data via SPC 63 to the CPU 69 of the digitalprocessor 4. If fed with the above-mentioned table data via SPC 63 fromthe information processing device 5, the CPU 69 of the digital processor4 routes the table data via buffer memory 65 to the LUTs 45R, 45G and45B. The data in the table memories 452R, 452G and 452B in the LUTs 45R,45G and 45B are re-written, based on the data supplied from the buffermemory 65, for doing optimum color balance adjustment.

[0084] If decision at step S12 is for ‘manual’, the informationprocessing device 5 awaits instructions at step S14 as to the correctionpoint and is actuated on user actuation.

[0085] At steps S14 and S15, grey balance is adjusted based on an imagedisplayed on the display unit 71 shown in FIG. 7. First, at step S14,the user designates, using the mouse 5A or the like, an area in thedisplayed image on the display portion 71 in which to effect greybalance. The information processing device 5 generates color balancecorrection data based on an image of the designated area. The correctiondata is sent at step S16 from the information processing device 5 to thedigital processor 4. The correction data is stored via buffer memory 65in the LUTs 45R, 45G and 45B in association with the designated area,that is in association with the signal level of the image in thedesignated area.

[0086] Referring to FIG. 10, there can be displayed, on the display 5Aof the information processing device 5, a camera/monitor selection unit81 for selecting which of the LUT values on the camera or the LUT valueon the monitor device 8 should be changed; a table editor portion 82 fordisplaying LUT data prior to adjustment as a graph; a color signalselection portion 83 for selecting which of the color imaging signals R,G and B should be used for the graph displayed on the table editorportion 82; a resetting portion 84 for resetting the data being adjustedfor colors by the table editing portion 82; a registration portion 85for registering the color-adjusted correction values; an inversionportion 86 of negative/positive inversion; a user table for displayingthe current LUT data (pre-correction LUT data); a call-out portion 88for calling out the past correction value registered by the user; and areturn portion 89 for reversion to the original picture.

[0087] In this case, the user can drag two black points on the tableediting portion 82 using a mouse for doing signal level adjustment ofthe color imaging data B displayed on the color signal selection portion83. Thus the user can obtain color imaging data adjusted to the desiredcolor balance as he or she views the display of the informationprocessing device 5.

[0088] If the user clicks the inversion portion 8, the CPU 69 of theimaging device reverses the characteristics of the LUTs 45R, 45G and 45Band the LUTs 49R, 49G and 49B based on the control signal from theinformation processing device 5. That is, the CPU 69 can reverse theusual right upward sloping LUT characteristics shown in FIG. 12 intoright downward sloping LUT characteristics shown in FIG. 13 forrealizing negative-positive converted color imaging data.

[0089] The user then sets the color imaging data B, for example, to adesired value, and clicks the registration portion 85. This causes theinformation processing device 5 to send data of the thus set value tothe digital processor 4. Since the data in the LUTs 45R, 45G and 45B arere-written, these LUTs can vary the levels of the color imaging data R,G and B supplied from the A/D converters 44R, 44G and 44B for realizingoptimum color balance adjustment.

[0090] Thus it is possible with the present imaging system to make colorbalance adjustment even in a grey area intermediate between the blackand the white which has not been possible with the conventional whitebalance adjustment.

[0091] Also, with the above-described imaging system, the color balancecan be adjusted easily and simply by designating an optional point of agraph of the LUT characteristics displayed on the display of theinformation processing device and by modifying the designated pointaccording to the taste of the user.

[0092] In addition, with the above-described imaging system, in whichcolor imaging data to the monitor device can be corrected by the LUT,the color balance adjustment can be realized as a whole in considerationof color variation between the monitoring device and the display of theinformation processing device.

[0093] With the imaging system, in which a particular object can bepre-arranged for setting the pickup point, color balance adjustment canbe automatically realized for the grey area from black to white.

[0094] With the present imaging system, the following sequence may beused for adjusting the table data controlling the level of the colorimaging data responsive to the color imaging signals. The table data aregenerated by the grey balance adjustment now explained.

[0095] The grey balance adjustment is performed in accordance with theflowchart shown in FIGS. 14 to 16.

[0096] First, the user prepares a white paper sheet at step S31, asshown in FIG. 14. At step S32, the user opens the diaphragm in order topermit the grey balance adjustment to be started at step S33. Theprocessing for grey balance adjustment is executed by the CPU 30 of thecamera head 3 and the CPU 69 of the digital processor 4.

[0097] In the grey balance adjustment, the white level is set to apre-set luminance level at step S41 in the flowchart of FIG. 15. Thewhite level setting is performed in accordance with the flowchart shownin FIG. 16.

[0098] That is, at step S32, the diaphragm is opened. Then, at step S51,it is checked whether or not the grey balance switch 9D is pressed. Ifthe grey balance switch 9D is pressed, processing transfers to the nextstep S52.

[0099] In the steps S52 to step S55, the imaging output of the whitepaper sheet is adjusted to a pre-set luminance level by changing one ofthe gain of the control circuit 24, diaphragm of the imaging lens 2, orthe signal charge accumulation time of the CCD image sensor 21, that isan electronic shutter.

[0100] The pre-set luminance level is set so that, if the signal levelof the color imaging signals R, G and B for the white paper sheet withthe diaphragm opened can be divided into 256 gradations, and the signallevel of the green-colored imaging signal G corresponds to the 256thgradation, the green imaging data G outputted by the gain controlcircuit 24 corresponds to the 210th gradation.

[0101] That is, the white paper sheet is imaged by the camera head 3with the diaphragm opened. An imaging output of the CCD image sensor 21of the camera head 3 is supplied via pre-amplification circuit 23 to thegain control circuit 24. An output of the gain control circuit 24, thatis green imaging data G, is supplied as a luminance level to the CPU 30.

[0102] At step S52, the CPU 30 checks if the luminance level of theimaging output of the white paper sheet is smaller than a pre-setluminance level. If the luminance level is smaller than the pre-setluminance level, the CPU 30 transfers to step S53 to increase the gainof the gain control circuit 24 in order to increase the luminance level.The CPU 30 then reverts to step S52 in order to check the luminancelevel of the imaging output repeatedly.

[0103] If it is found at step S54 that the luminance level of theimaging output is not smaller than the pre-set luminance level, the CPU30 transfers to step S54. If the luminance level of the imaging outputis larger than the pre-set luminance level, the CPU 30 transfers to stepS55 in order to control the diaphragm of the imaging lens 2 or thesignal charge accumulation time of the CCD image sensor 21, that is theelectronic shutter, for decreasing the luminance level. The CPU 30 thenreverts to step S52 in order to check the luminance level of the imagingoutput repeatedly.

[0104] The above-mentioned control of the electronic shutter isperformed by the CPU 30 changing the signal charge accumulation time ofthe CCD image sensor 21 via timing generator 34 and CCD driver 35.

[0105] If the white level is set at step S41 in the flowchart of FIG. 15to a pre-set luminance level, the CPU 30 of the camera head 3 transfersto step S42 to instruct the digital processor 4 to capture the imagingdata R, G and B into the frame memory 56. The imaging data R, G and B,once captured by the frame memory 56, are read from the frame memory 56so as to be captured by the information processing device 5.

[0106] At step S43, color balance correction data is formulated by theinformation processing device 5. Such correction amounts R′ and B′, thatwill give R=G=B based on imaging color data G of the color imaging dataR, G and B, are calculated. R′ and B′ are found from R′=R-G and B′=B-G,respectively. Based on the calculated correction amount data R′ and B′and the color imaging data R, G and B, table data in the table memories452R, 452G and 452B in the LUTs 45R, 45G and 45B are re-written at stepS44 by the CPU 69 of the digital processor 4.

[0107] That is, if the correction data R′ and B are fed from theinformation processing device 5 to the SPC 63, the CPU 69 of the digitalprocessor 4 writes table data in the table memories 452R, 452G and 452Bin the LUTs 45R, 45G and 45B via buffer memories 65.

[0108] At step S45, it is checked whether or not the color imaging dataR, G and B captured by the information processing device 5 via framememory 56 are of the black luminance level. If the color imaging dataare judged at this step S45 not to be of the black luminance level,processing transfers to step S46 in order to control the light exposurevolume. At this step S46, a command is sent from the informationprocessing device 5 to the CPU 30 of the camera head 3 in order for theCPU 30 to control the charge accumulation time of the CCD image sensor21 or the light stop value of the imaging lens 2. For light exposurevolume control, a system of controlling the signal charge accumulationtime under constant light stop value or a system of controlling thelight stop under constant signal charge accumulation time may beselectively used such that the light exposure volume control as selectedby the user is executed by the system.

[0109] In the light exposure volume control under constant light stop,the signal charge accumulation time of the CCD image sensor 21 is variedfor lowering the effective light exposure volume. In the light exposurevolume control under constant signal charge accumulation time of theelectronic shutter, the light stop value of the imaging lens 2 ischanged for lowering the light exposure volume at the time of imaging.

[0110] After lowering the light exposure volume, processing transfers tostep S43 again for calculating the correction amounts R′ and B′ based onthe color imaging data R, G and B. The color imaging data R, G and B andthe correction amounts R′ and B′ are written at step S44 from theinformation processing device 5 via buffer memory 69 in the tablememories 452R, 452G and 451B of the LUTs 45R, 45G and 45B.

[0111] The processing from step S41 to step S46 in the flowchart of FIG.15 is continued until the luminance level reaches the black level atstep S45. This gives adjustment data for each grey level. When theluminance level reaches the black level, table data formulation by greybalance adjustment at step S33 shown in FIG. 14 comes to a close.

[0112] If the diaphragm or the signal charge accumulation time of theelectronic shutter is controlled so as to be changed at a pre-set value,gradation control from the white level to the black level, executed ingrey balance adjustment, can be changed continuously. This gives adesired number of samples from the white level to the black level.

[0113] With the table data, thus adjusted for grey balance, can be usedfor performing optimum color balance adjustment on subsequently inputtedcolor imaging signals of the object, that is on color imaging data R, Gand B supplied from the A/D converters 44R, 44G and 44B. In this manner,color-balance adjusted camera side color imaging data R, G and B areoutputted via D/A converter.

[0114] In this manner, with the present imaging system, color balanceadjustment can be achieved even in a grey area intermediate between theblack and white, which has not been possible with the conventional whitebalance adjustment.

[0115] Also, with the imaging system, color balance can be adjustedeasily and simply by designating an optional point of the imagedisplayed on a display of the information processing device and bymodifying the desegrated point depending on the liking of the user.

[0116] In addition, with the imaging system, color balance adjustment inthe grey area from black to white can be achieved automatically byarranging a specified object for setting a pickup point.

1. A color imaging apparatus comprising: imaging means for imaging anobject for generating a color imaging signal made up of a plurality ofcolor signals; level balance control data generating means forgenerating level balance control data based on the relative relationbetween signal levels of the color signals; light exposure volumeadjustment means for adjusting the light exposure volume of said imagingmeans; memory means for storing, in each light exposure volume adjustedby said light exposure adjustment means, the level balance control datagenerated by said level balance control data generating means, inassociation with signal levels of said color signals in each lightexposure volume; and level balance control means for reading out thelevel balance control data associated with said color signals from saidstorage means, based on the signal level of each of said color signals,for controlling the signal level of each color signal.
 2. The colorimaging apparatus as claimed in claim 1 wherein said level balancecontrol data generating means generates said level balance control datain an adjustment mode; and wherein said level balance control meanscontrols the signal level of each color signal at least in an imagingmode.
 3. The color imaging apparatus as claimed in claim 2 wherein, insaid adjustment mode, said light exposure volume adjustment meansadjusts the light exposure volume of said imaging means to a pre-setlight exposure volume prior to generation of said level balance controldata by said level balance control data.
 4. A color imaging methodcomprising the steps of: imaging an object to generate a color imagingsignal made up of a plurality of color signals; generating level balancecontrol data based on the relative relation between signal levels of thecolor signals; storing said level balance control data in each lightexposure volume adjusted by light exposure adjustment means inassociation with the signal levels of said color signals in each lightexposure volume; reading out stored level balance control data based onthe signal level of said color signals; and controlling the level ofeach color signal based on the read-out level balance control data.
 5. Acolor imaging apparatus comprising: imaging means for imaging an objectfor generating a color imaging signal made up of a plurality of colorsignals; pre-set area extraction means for sequentially extracting colorimaging signals of portions representing images in a plurality ofpre-set areas in a picture represented by said color imaging signals;level balance control data generating means for generating level balancecontrol data based on the relative relation between signal levels of thecolor signals contained in said pre-set areas; storage means for storingsaid level balance control data in association with the relativerelation of the signal levels of the color signals contained in saidpreset areas; and level balance control means for reading out said levelbalance control data from said storage means in association with saidcolor signals based on the signal levels of the color signals forcontrolling the signal levels of the color signals.
 6. The color imagingapparatus as claimed in claim 5 wherein said level balance control datagenerating means generates said level balance control data in anadjustment mode; and wherein said level balance control means controlsthe signal level of each color signal at least in an imaging mode. 7.The color imaging apparatus as claimed in claim 5 wherein said objecthas different lightnesses from one pre-set area to another.
 8. A colorimaging method comprising the steps of: imaging an object to generate acolor imaging signal made up of a plurality of color signals;sequentially extracting color imaging signals of portions representingimages in a plurality of pre-set areas in a picture represented by saidcolor imaging signals; generating level balance control data based onthe relative relation between signal levels of the color signalscontained in said pre-set areas; storing said level balance control datain association with the relative relation of the signal levels of thecolor signals contained in said preset areas; reading out the storedlevel balance control data based on the signal levels of the colorsignals; and controlling the signal levels of said color signals basedon the read-out level balance control data.
 9. A color imaging apparatuscomprising: imaging means for imaging an object for generating colorimaging signals made up of a plurality of color signals; display meansfor displaying an image based on said color imaging signals; areadesignation means for designating a desired area in said image displayedby said display means; level balance control data generating means forgenerating level balance control data based on the relative relationbetween signal levels of the color signals constituting said colorimaging signals corresponding to the area designated by said areadesignating means; storage means for storing said level balance controldata in association with the signal levels of the color signals in thearea designated by said area designating means; and level balancecontrol means for reading out said level balance control data associatedwith respective color signals from said storage means based on thesignal levels of the color signals for controlling the signal levels ofthe color signals.
 10. The color imaging device as claimed in claim 9wherein said level balance control data generating means generates saidlevel balance control data in an adjustment mode; and wherein said levelbalance control means controls the signal level of each color signal atleast in an imaging mode.
 11. A color imaging method comprising thesteps of: imaging an object to generate color imaging signals made up ofa plurality of color signals; displaying an image based on said colorimaging signals; designating desired areas in the displayed image;generating level balance control data based on the relative relationbetween signal levels of the color signals constituting said colorimaging signals corresponding to the designated area; storing said levelbalance control data in association with the signal levels of the colorsignals in each of the designated areas; reading out stored levelbalance control data based on the signal levels of the color signals;and controlling the signal levels of the color signals based on theread-out level balance control data.